This invention relates to a fan and, more particularly, to a compact, lightweight, low inertia fan configured to be used, for example, with a radiator for cooling an automobile engine.
Water or a coolant for liquid cooled automobile engines is conventionally circulated through a radiator. Such radiators are provided with fans which draw air through the radiator to cool the water or coolant which, in turn, cools the engine. Typically, the fan is connected to a pulley which is driven by the engine. The pulley, pulley drive and fan take up considerable space in the engine compartment. Furthermore, the fan is driven continuously while the engine is in operation and adds to the load on the engine. Such load is added even though, at start up and at high speed in cooler weather, air circulation by the fan through the radiator to cool the water or coolant may not be necessary. Indeed, automobile engines are typically provided with thermostats which prevent water or coolant circulation through the engine and radiator until the engine temperature reaches a predetermined value.
In some foreign cars, sports cars and, more recently, in U.S. manufactured cars with transversely mounted engines, the engine driven fan has been replaced with a fan driven with an electric motor. In such electric motor driven automobile radiator cooling fans, the pulley has been replaced with a conventional electric motor. The overall length of the fan assembly, with such an electric motor, is substantially equal to or slightly longer than the pulley-fan arrangement. The electric motors in such arrangements are, in many instances, thermostatically controlled to stop and start as engine cooling is required. However, the overall size and weight of the fan assembly and its electric motor necessitate care in the arrangement of mounting structures and in the placement of other components of the automobile to provide space for the fan assembly and its drive motor.
Since at least as early as July/August 1975, in an article at pages 34,35 of Automotive Design Engineering by P. Campbell and A. E. Corbett, it has been proposed to employ pancake or printed circuit motors in radiator cooling fan drives. In such proposed printed circuit motors, the brush gear was positioned between adjacent magnets for engagement with a commutator extending circularly around and axially along the axis of motor rotation. Thus, the brushes contacted the armature in a direction normal or at right angle to the axis of rotation of the motor and fan.